Intermittent Fault Detection & Isolation System (IFDIS) · fault at the precise moment the fault occurs or the fault is missed completely, the result is No Fault Found. *Note –

Department of Defense Maintenance Symposium and Exhibition November 13-16, 2012

Intermittent Fault Detection & Isolation System (IFDIS)

Mr. Ken Anderson Vice President

Universal Synaptics Corp.


Problem

• Approximately 50% of the malfunctioning LRUs/WRAs inducted into the depot for repair are not actually repaired

– Test No Fault Found (NFF)

– Disassembled, Cleaned & Reassembled (DCR)

– Circuit cards are reseated

– SRUs/SRAs are replaced which subsequently test NFF

• NFF activity costs DoD $2B to $10B annually

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Problem

• Conventional test equipment is incapable of detecting intermittent circuits in LRU/WRA chassis

– Cracked solder joints

– Loose wire wraps

– Loose crimp connections

• These electromechanical devices fail intermittently long before they fail permanently

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Problem

• Consistent discontinuity (hard failure) can be detected using

conventional equipment

• Intermittent discontinuity is very short in duration

• Often only seen during stress situations

– High G loading – Thermal extremes

– Vibration – Combination of stresses

• Conventional testers are not designed to detect intermittent

faults

– Test one circuit or function at a time (sequential testing)

– Scans, samples or averages intermittent faults out

– Lack of test coverage and sensitivity to detect random intermittent faults that cause NFF

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Solution

• Build a tester specifically designed to detect and isolate intermittent circuits

– Must monitor ALL circuits (parallel testing) in a unit under test (UUT) ALL the time to prevent missing any random intermittent event

– Must be sensitive enough to detect nanosecond range intermittent events

– Must simulate operational environment

• The Intermittent Fault Detection & Isolation System (IFDIS) is such a tester

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• Intermittent Fault Detector developed and patented by Universal Synaptics – Hardware neural network analog instrument – Individually, simultaneously and continuously monitors

thousands of circuit paths – Detects and records all momentary discontinuities as short

as 20 nanoseconds

• Shake table • Environmental chamber • Interface Test Adaptor (ITA)

IFDIS Major Components

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IFDIS

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Conventional Tester Probability of Detecting a Random Intermittent Event

.03% detection probability

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IFDIS Probability of Detecting a Random Intermittent Event

9

100% detection probability



Mr. Sami Mansour Director

523rd EMXS, USAF

O G D E N A I R L O G I S T I C S C O M P L E X

Air Force Problem

Conventional testers are unable to detect the problem in F-16 Modular Low Power Radio Frequency (MLPRF) LRUs 51% of the time

Discovered chassis intermittent circuits in 1999 Using a microscope, found ribbon cable had

cracked solder joints

MLPRF SRUs had 90% NFF rate

Initiated massive ribbon cable re-soldering program

No depot tester could detect intermittent circuits

Built Right...Ready to Fight


Air Force Solution

Discovered IFDIS capability in 2006

Stood up two systems in 2009 through SBIR Phase III vehicle

One in F-16 MLPRF repair shop

One in “Bad Actor” laboratory

IFDIS Tested over 400 MLPRFs

Over 25 times ($56M) return on investment


MLPRF Chassis


MLPRF With ITA Installed


MLPRF Ribbon Cable & Wiring


MLPRF Results

Intermittent faults detected and isolated in over 58% of the units IFDIS tested (over 400 MLPRFs)

Increased Mean Operating Hours Between Depot Repair from 290 to 926 hours (more than Tripled)

Near the top of the MICAP list for over a decade, now not even on the MICAP list

Troubleshooting time reduced by over 50%

Over 25 times ($56M) return on investment


Future

Recently started IFDIS testing F-16 Radar Antenna

Plan to stand up 8000+ channel system in 2013

Capable of testing F-16 Programmable Signal Processor (PSP) – Unreliable & costly to sustain

Plan to expand IFDIS testing to many LRUs

Will be capable of testing virtually any LRU in the USAF inventory, as well as Joint Service LRUs


F-16 Radar Antenna with ITA


F-16 PSP


Air Force Summary

IFDIS was great investment – amazing ROI

Solving our intermittent / NFF circuit problem

Reliability improvement greater than expected

Reducing Air Force maintenance costs

Expanding to other LRUs as rapidly as possible

Next year should have large enough IFDIS to test any LRU in the USAF inventory, as well as Joint Service LRUs



Mr. Brett Gardner Avionics Advanced Aircraft Technologies (AAT)

Team Lead, FRC SW


Navy Intermittent Fault Issues

• Intermittent / No fault found (NFF / A799) circuit problem with all Navy WRAs chassis

• F/A-18 Generator Convertor Unit (GCU) consistently appears on the F/A-18 top degrader list – GCU chassis currently tested with conventional continuity

tester

– Intermittent circuit detection extremely limited using conventional tester

• IFDIS technology was investigated by AAT 2010

• NAVSUP/F18 PMA funded GCU/IFDIS test demonstration

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GCU Chassis

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GCU Tied to IFDIS

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GCU Intermittent Wire

XA3-89

IFDIS precisely detected and isolated one or more intermittent circuits in 80% of the GCUs tested

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Navy Results

• Selected (5) Ready for use (RFU) F18-C GCU chassis for IFDIS testing

• IFDIS detected and isolated intermittent circuits in 80% of the RFU GCU Chassis

• IFDIS stand up 2014 at FRCSW as part of Capital Improvement Program (CIP)

• Several other FRCSW NAE top degrader chassis are in the pipeline for IFDIS testing at FRCSW Depot, APG-73/65, E2 MC, F18 E/F/G GCU

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Navy Results Cont. • IFDIS is self learning – requires limited engineering

oversight and $$ to program • Repeatable results – Operator can repeat testing as

required to verify vibration and temperature related faults • Verification – Once repaired, chassis is re-run on IFDIS to

verify repair • Cable assemblies and hold down fixtures manufactured

locally at low $$ using standard parts readily available in supply

• Interface compatible with Automated Wire Test Set (AWTS) – Leverage off of I-level AWTS interface – Systems deployed with AWTS IDs compatible with IFDIS

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Questions?

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Back up slides

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Pin not soldered

Intermittent Fault Causes

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Intermittent Fault Causes

Cracked Solder

Joint

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Conventional Automatic Test Equipment (ATE)

TP1 TP2 TP3 TP4

TP1 TP2 TP3 TP4

25ms 5ms

60ms of testing 1360ms missed 4% Test Coverage

IFDIS

0 360ms

1340ms of testing 100ms missed 93% Test Coverage

I99.99% for a 30min test

*Note – Conventional ATE scanning measurement window must perfectly synchronize with fault at the precise moment the fault occurs or the fault is missed completely, the result is No Fault Found.

*Note – All lines All the time test coverage equals no missed defects!

Test Coverage 101

Intermittent Fault Detection & Isolation System (IFDIS) · fault at the precise moment the fault occurs or the fault is missed completely, the result is No Fault Found. *Note –

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